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3 Department of Electrical and Computer Engineering PDR Recap  Project Goal Give people a means to monitor and control the electrical devices within their households.  Motivation Energy conservation has a significant social & economic impact. It is hard to conserve energy because Limited quantitative data Limited social awareness Limited residential control

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8 Department of Electrical and Computer Engineering Design Choice: P4400 Watt Meter watt meter analog board schematic showing the input and output from the wall socket, as well as the probe points for the current sense resistor

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9 Department of Electrical and Computer Engineering Design Choice: P4400 Watt Meter watt meter transformer less power supply schematic showing the input from the analog board and the output connections to the microchips

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10 Department of Electrical and Computer Engineering Design Choice: P4400 Watt Meter watt meter LM2902 quad op amp schematic showing the input from the analog board and power supply followed by the output connections to the microcontroller

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11 Department of Electrical and Computer Engineering Design Choice: Proprietary Design transformer less power supply design schematic for a 15V and 50mA output. The top right graph shows the simulated 15V voltage output and the bottom right graph shows the simulated 50mA current output.

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12 Department of Electrical and Computer Engineering Design Choice: Proprietary Design Initial PCB layout for the transformer less power supply design schematic with a 15V and 50mA output.

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13 Department of Electrical and Computer Engineering Design Choice: Proprietary Design Utilization of instrumentation amplifier chosen for high CMRR. This is essential to provide greater precision for measuring differential voltage across a current shunt resistor. This chip has an CMRR of 120dB.

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14 Department of Electrical and Computer Engineering Design Choice: Proprietary Design Using the current design of the XBee Explorer as a foundation, the final implementation of the watt meter PCB will have a subsystem with pin out headers for easy insertion of an XBee module

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18 Department of Electrical and Computer Engineering Design Choice: Transmission Frequency  One of the problems encountered in the transmission of data between the XBee and Raspberry pi was generating the necessary current from the Kill-a-Watt device.  In the initial approach to this solution we use a 10000uF capacitor biased at 5V to yield a 50mA current. Based on the following formula, we calculated the discharge time to be approximately 17 ms, which would simulate the period of a sine wave at 60Hz. Where Vo = 5V R = 100 ohm and C = 10000uF

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29 Department of Electrical and Computer Engineering Kevin’s MDR Goals/Progress  Develop a Basic user interface prototype that is functional across all operating system  Come up with a plotting functionality  Demonstrate plotting data by successfully querying from the database  Function to take in user input and manipulate the data as specified  Function to assimilate new devices to the system  Function to receive and send relay Signal

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33 Department of Electrical and Computer Engineering User Interface CDR Goals  Develop a function to take in user input and manipulate the data as specified then plot the data  Develop a function to assimilate new devices to the system  Develop a function to receive and send relay signals